The prescribing information for Propecia (finasteride 1 mg) states that, in general, daily use for three months or more is necessary before benefit is observed. It also states that continued use is recommended to sustain benefit and that withdrawal of treatment leads to reversal of effect within 12 months. This guide reports what the label's studies measured. It does not predict a result for any one man.
Timing in the label
Besides the three-month statement, the label says patient self-assessment showed overall improvement compared with placebo as early as 3 months (p<0.05), with improvement maintained over 5 years.
What the studies measured
The label describes three double-blind, randomized, placebo-controlled studies of 12-month duration. The two primary endpoints were hair count and patient self-assessment. The two secondary endpoints were investigator assessment and ratings of photographs. The label states that hair counts were assessed by photographic enlargements of a representative area of active hair loss. It also states that all men, whether treated with finasteride or placebo, were instructed to use a specified, medicated, tar-based shampoo.
| Measure at 12 months | What the label states |
|---|---|
| Hair count | A 107-hair difference from placebo. |
| Further hair loss (any decrease in hair count from baseline) | 58% of men in the placebo group, compared with 14% of men treated with Propecia. |
| Investigators rated hair growth as increased | 65% of men treated with Propecia, compared with 37% in the placebo group. |
| Independent panel photograph ratings showed an increase | 48% of men treated with Propecia, compared with 7% of men treated with placebo. |
The label also reports 5-year results:
- Hair count was maintained above baseline throughout the 5 years, and the difference between treatment groups continued to increase, resulting in a 277-hair difference.
- At 5 years, 100% of men in the placebo group demonstrated hair loss, compared with 35% of men treated with Propecia.
- At 5 years, investigators rated 77% of men treated with Propecia as having increased hair growth, compared with 15% of men treated with placebo.
- In the 5-year photographic assessment, 48% of treated men demonstrated an increase in hair growth, 42% were rated as having no change and 10% as having lost hair compared to baseline. For men on placebo, the figures were 6%, 19% and 75%.
What the sources say about stopping
The label states that withdrawal of treatment leads to reversal of effect within 12 months. It reports that a change of treatment from Propecia to placebo (n=48) at the end of the initial 12 months resulted in reversal of the increase in hair count 12 months later, at 24 months.
Effects the label reports as continuing after stopping
The same label lists, among adverse reactions identified during post-approval use, sexual dysfunction that continued after discontinuation of treatment, including erectile dysfunction, libido disorders, ejaculation disorders, and orgasm disorders. Its Patient Information lists depression; suicidal thoughts; and decrease in sex drive that continued after stopping the medication among effects reported in general use. The statements used here give no rate for these reports, so they cannot be compared with the trial percentages above.
What this does not tell you
Trial figures describe groups of men. They do not show what any one man will see. In the 5-year photographic assessment, men in the treated group were not all rated the same way: 48% increase, 42% no change, 10% lost hair.
The label says its efficacy was demonstrated in men (88% Caucasian) with mild to moderate androgenetic alopecia between 18 and 41 years of age. Hair counts were assessed on photographic enlargements of a representative area of active hair loss. The three-month statement begins "in general", and the sources used here do not say when any one man would notice a change.
The reversal figures come from the label's general statement and from a switch-to-placebo group of 48 men. Decisions about starting, continuing or stopping belong to the person and a licensed provider.